1. Field of the Invention
The present invention relates to an image forming apparatus, and more particularly, to an image forming apparatus for carrying out nozzle cleaning of a recording head by preliminary discharge of ink onto a conveyance belt.
2. Description of the Related Art
An image forming apparatus based on an inkjet method forms images on recording paper by discharging ink onto recording paper from a recording head while conveying recording paper by means of a conveyance belt. In an image forming apparatus of this kind, in order to clean and prevent drying of the nozzles of the recording head which are in contact with the external air at all times, a preliminary discharge (purge, blank discharge, liquid discharge) is carried out from the nozzles, into an ink receiving part, at prescribed time intervals. However, there is a problem in that a separate ink receiving part is required. Japanese Patent Application Publication No. 9-109377 discloses technology to resolve this problem wherein an ink receiving section is provided on the conveyance belt, and furthermore, ink is removed from the ink receiving section by dropping off naturally when the ink receiving section of the conveyance belt is facing downwards.
In the image forming apparatus of this kind, however, if the amount of ink expelled in the preliminary discharge is a very small amount (for example, several picoliters), then the solvent component of the ink will evaporate very rapidly, and the ink will solidify on the conveyance belt, and hence the ink will not be readily removable (it will not readily drop off in a natural fashion).
Furthermore, in Japanese Patent Application Publication No. 9-109377, since the ink receiving part is formed in a particular position of the conveyance belt, there has been a problem in that preliminary discharge cannot be carried out at any desired position on the belt, and productivity in image forming declines.